1 × 104 HepG2 cells were platted in 96-well plates and cultured in Dulbecco's modified eagle medium (DMEM, Gibco, NY, USA) with 10% fetal bovine serum (FBS, Invitrogen, Life Sciences, USA) and 0, 0.25, 0.5, 1, 2 millimole per liter (mM) SA, OA, LA, and ALA, respectively, for 24 h. Then, 10 μL of 5 mg/ml MTT was added into each well and 4 h incubation at 37°C was needed. Discard the supernatant. One hundred fifty microliters of dimethyl sulfoxide (DMSO, Jiancheng, Nanjing, China) was added into each well and incubated at 37°C for 10 min. Formazan in living cells was solubilized by DMSO. The absorbance was measured at 490 nm with a microplate reader (Bio-Rad iMark, USA).
